A subordinate character can be defined as a character with an important role in a story who is not actually the story's protagonist. Subordinate characters often either motivate the protagonist or set out obstacles that the protagonist must surmount.
Examples of subordinate characters in literature include the ghost of Hamlet's father in "Hamlet" or Sancho Panza in "Don Quixote."
Subordinate characters play roles that help the story's plot move forward, while minor characters are not as crucial to the plot. In the movie "Star Wars: A New Hope," for example, Obi-Wan Kenobi is a subordinate character, while Greedo is a minor character.